Confocal microscopy of Spitzenkörper dynamics during growth and differentiation of rust fungi

Area of Science:

• Mycology
• Cell Biology
• Plant Pathology

Background:

• The Spitzenkörper is a key organelle in fungal hyphal tip growth.
• Its precise role in vesicle transport and growth dynamics requires further elucidation.
• Rust fungi like Uromyces vignae and Puccinia graminis exhibit specialized growth structures.

Purpose of the Study:

• To visualize and characterize the Spitzenkörper in rust fungi germlings.
• To investigate the dynamic behavior and positioning of the Spitzenkörper during hyphal growth and differentiation.
• To assess the Spitzenkörper's role in supplying secretory vesicles for germ tube elongation and appressorium formation.

Main Methods:

• Utilized the membrane-selective fluorescent dye FM4-64 for staining.
• Cultured rust fungi (Uromyces vignae, Puccinia graminis) on glass surfaces.
• Employed confocal microscopy with optical sectioning to observe stained hyphal tips.

Main Results:

• FM4-64 effectively stained the Spitzenkörper within 15 minutes.
• The Spitzenkörper was asymmetrically positioned near the cell-substratum interface during germ tube growth.
• Dynamic changes in Spitzenkörper shape and position were observed, correlating with new growth regions.
• The Spitzenkörper disappeared during appressorium differentiation but reappeared during penetration peg formation.

Conclusions:

• The Spitzenkörper actively supplies secretory vesicles essential for rust fungi germ tube growth.
• Its dynamic nature and positioning are critical for directed hyphal tip extension.
• The Spitzenkörper plays a role in both initial germ tube growth and subsequent infection structure development.